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G. W. BROWN. AUTOMATIC FIRE ALARM SYSTEM.

Patented Nov. 17,1891.

Z Fig.6.

(No Model.)

3 Sheets-Sheet 3.

G. W. BROWN.

AUTOMATIC FIRE ALARM SYSTEM.

Patented Nov. 17, 1891.

in: News Incas cm, wmwuma, WASHINGTON o c NlTED STATES PATENT FFICE.

GILMAN W. BROWN, OF VEST NEW'BURY, MASSACHUSETTS, ASSIGN OR OF ONE-HALFTO HAYDEN BROWN, OF SAME PLACE.

l AUTOMATIC FIRE-ALARM. SYSTEM.

SPECIFICATION forming part of Letters Patent No. 463,608, dated November17, 1891. Application filed August 21, 1891. Serial No. 403,377 (Nomodel.)

To all whom it may concern: will be pointed out in the claims at the endof Be it known that I, GILnAN BROWN, of this specification. WestNewbury, in the county of Essex and Figure 1 is an elevation of thereceiving- State of Massachusetts, have inventedcertain instrumentemployed on an automatic the 5 new and useful Improvements in Automaticalarm system embodying my invention. Fig. Fire-Alarm Systems, of whichthe following is 2 is a sectional detail, on an enlarged scale, of aSpecificationthe upper portion of the receiving'instrument,

This invention in automatic fire-alarm systhe section being taken on theline 2 2; Figterns has for its object to provide a novel sys- 3, a topor plan view of a thermostat embody- 1o. tem, as will be described,whereby the sounding my invention, the thermostat being shown ing offalse alarms is obviated and the sysin operative condition; Fig. 4,alongitudinal tern rendered more reliable in case of fire. section ofthe thermostat shown in Fig. 3 on In accordance with my invention one orline 4 4; Fig. 5, an under side view of-the more thermostats constructedas will be dethermostat shown in Fig. 3; Fig. 6, alongio 5 :5 scribedand located in a building or structtudinal section of the thermostat,shown in ure to be protected are included in a nor- Fig. 3 on line t 4,showing the thermostat as inally-closed circuit supplied with currenthaving been operated. Fig. 7 is a diagram from a battery or othersuitable source of of circuits showing two thermostats asconelectricity, and provided at amain or-central nected to thereceiving-instrument, only a 0 2o station with a receiving-instrumentconsistportion of the case of which is shown, the in g,essentially,of anaudible signal controlled thermostats being in their operative positionsby the polarized armature of an electro-magready to send in an alarm oftire; and Fig. 8, net. The thermostat referred to is cona diagram ofcircuits, showing the thermostrncted, as will be described, so as toprostats connected to the operative parts of the 25 duce reversals ofthe current over the main receiving-instrument, the thermostats beingline and thereby operate the electro-magnet shown as having beenoperated by a fire. to sound the audible signal in case of a fire. Thereceiving-instrument of my improved The receiving-instrument,preferably, also automatic fire-alarm system consists, essencomprises avisual indicating-instrument by tially, of an audible signal, (shown asan 30 which the condition of the l ne-circuit mayelectro-mechanically-operated gong or bell,) be made known to theoperator or attendant of any usualor well-knownconstruction,itcon- V atthe fire-station or central oflice. The p0 sisting of a striker or anarm a, secured to a larized armature of the electro-rnagnet is shaft Ct,having the crank-arm a joined by preferably adjusted so as to bewithdrawn a connecting-rod a to a pivoted arm a pro- 3 5 from itselectro-magnet when the strength of vided with a detent a co-operatingwith a the current flowing over theline falls below detent on a lover orarm a having at its upthe normalas, forinstance,in case of a weakper enda detent 0 (shown in dotted lines in d ening of the battery, ashort-circuiting of the Fig. 1,) with which co-operates a detent a online, ora dead break in the line, the withan armature-carrying lever apivoted as at 40 drawal of the armature operating the audible a andprovided with an armature a for an signal to call the attention of theoperator at electro-magnet a, suitably supported within the centraloffice to the factthat a change in the case a of thereceiving-instrument. The the condition of the main line has takenpivoted arm a is rotated in the usual man: place. The visualindicatingdevice referred ner, as herein shown, by a system of gears or 5 45 to ispreferably provided with a scale suitably clock-work (L15, actuated by anormally-woundmarked to indicate a weakening of the batup spring a, oritmay be a weight. The tery, a broken line, or a tire, whereby theatarmature (L of the electro-magnet is prefertendant upon hearing thealarm may see at a ably composed of hardened steel and polarglance underwhat condition the line-circuit ized or made apermanent magnet, andunder o is placed. normal conditions the polarity of the electro- Theparticular features of my invention magnet a is such as to attract thearmature (L and place the detent a 011 the armaturelever a" in the pathof movement of the detent a on the arm a, and thereby prevent themovement of the pivoted arm a and consequently hold the striker on thearm a away from the gong or bell A.

In accordance with my invention, the polarized armature a of theelectro-magnet is repelled away from the poles of the magnet (L by areversal in the current flowing over the line in which theelectro-magnet a is located. The reversal of the current is effected bymeans of a polechanging thermostat, preferably constructed as shown inFigs. 3 to 6, inclusive. The thermostat consists, essentially, of ablock or supporting-base b of insnlating material-usuallywood,porcelain, or hard rubber-and provided on one face with two springs L 6(shown as flat strips of 1netal,) constituting the other set ofpolechanging arms for. the thermostat. These springs are firmly securedto the base I) at one end, they being herein shown as bent down over therear side of the block b, and the said strips have secured to thembinding screws 11 5*, respectively, to which the line-wires are secured,as will be described. of the strips l) b are normally secured by afusible material or soldersuch as an alloy of lead, tin, cadmium, &c.-toconductingstrips 11 Z). (Shown in Figs. 3 to 63, inclusive, as securedto the front side of the block or su pporting-base b.) Theconducting-strips b Z2, as herein shown, have secured to thembindingscrews U 11 by which the line-wires may be connected with thethermostat. The springstrips Z) l) have secured to them on their underside projecting pole-changing arms Z) b one of which is shown in fulllines, Figs. 4 and 6, and both of which are indicated by dotted lines inFig. 5. The pole-changing arms 6 b project into a recess or cavity 11 inthe base I) and co-operate with the circuitterminal, herein shown asrods or bars Z1 I), extending across the said recesses. Thecircuit-terminal Z1 is connected by a conductjug-wire (J to thebinding-screw b and the circuit-terminal b is connected byconducting-wire Z1 to the binding-screw b, as clearly shown in Fig. 5.The pole-changing arms b" b as herein shown, are provided with fingers,which extend under the circuit terminals b b when the thermostaticsprings Z) b are in their normal condition, (shown in Figs. 3 and 4,)but which are adapted to be brought up into contact with thecircuit-terminals Z2 12 when the thermostatic springs are released bythe melting of the solder or fusible connection, as in the case of afire. This position of the thermostatic springs is indicated in Fig. 6.In the normal condition of the system the thermostatic springs b b aresecured to the contact-strips B Z) by the fusible connection, and thearmature (e is attracted by its magnet a, the current flowing over theline in what may be termed the normal direction, as indicated by the ar-The free en derow 20 in Fig. 7. ll. now the thermostat should beoperated, as by the breaking out of a fire in its vicinity, thethermostatic springs 1') b being released by the melting of a fusibleconnection, would fly upward and thus brihg the pole-changing arms I) Z2into contact with the circuit-terminals D b, in which case the current.would flow over the line, as indicated in Fig. 8, it passing from thepositive pole of the battery Bin the direction indicated by arrow 20until it came to the spring b and the connection between the spring 11and its cooperating strip I) being interrupted, the current will flowdown the pole-changing arm, as indicated by arrow 21, and by thecircuit-terminal b and wire b to the binding-screw I)", from whence itwould pass into the receiving-instrument, and through the electro-magneta, in a reverse direction, and thence out over the line again to thebindingscrew [1 from whence it would pass by the conducting-wire Z1 andterminal I) to the polechanging arm and thence by the spring I) to thenegative pole of the batter By the reversal of the current over the mainline, as thus described, the polarized armature a is repelled by itsmagnet (L13 and the armature lever a is turned on its pivot a so as towithdraw the detent a from engagement with the detent a 011 the lever a,and thereby permit the spring or motor a to turn the pivoted arm a andthe striker-arm a and sound the gong or bell A, thus giving an alarm atthe receiving-instrument that a change in the condition of the circuithas been effected.

In order that the operator at the central oiiice may positively knowwhether the alarm thus sounded is due to the. operation of thethermostat or to a broken wire or for other cause, an indicating device,preferably visual, is employed, which may be and preferably is locatedwithin the case a. The indicating device, as herein shown, consists of agalvanometer-coil 0, having pivotally suspended within it a polarizedneedle 0, preferably of hardened steel, mounted on a shaft or arbor 0within the coil 0, said 'arbor having secured to it a pointer 0 whichco-operates with the plate or dial 0 secured in a suitable manner to theframe-work of the case. The dial a, as herein shown, (see Fig. 1,) isprovided with four graduations or indications marked, respectively,- OK,battery run down, line broken, and fire, the line-broken indicationoccupying a central or zero position on the scale. It thegalvanometer-coil is not being traversed by an electric current, thepointer 0" would stand on the zero position or line-broken indication,and when the current is traversing the coil in its normal direction thepointer 0 will be turned to one side of the zero position-as, forinstance, to the left, as shown in Fig. 1-and when the current isreversed, as has been described, the pointer will be deflected to theindication marked fire. The attendant at the main oifice by glancing atthe dial might ascertain from the pointer the fact that the battery hadbeen weakened; but in order to render this feature more positive Iprefer that the alarm or audible signal a should also be sounded whenthe battery is thus weakened. This may be accomplished by adjusting thetension of the retractor for the armature a, which retractor is hereinshown as a spiral spring d. When the battery has been weakened, thespring (1 will withdraw the armature a from its electromagnet andrelease the motor mechanism and sound the alarm A. In case of a brokenwire the current will cease fiowingover the mainline and the pointer 0will fall to zero or to the indication marked brokenline. So, also, ifthe main line should be short-circuited the same effect would beaccomplished, and in either case the armature 0/ would be withdrawn byits spring (1 to start the motor and operate the alarm. In the normalcondition of the main line the pointer 0 stands at the indication OK;but when the thermostat is operated, as by the breaking out of a fire,the current is reversed and the pointer 0 will pass beyond the zeroposition to the other side toward the indication marked fire. In thisway the operator at the fire or receiving station is enabled to knowpositively for what cause the alarm has been sounded; or, in otherwords, the true condition of the line-circuit at all times is made knownto him, so that in case of any accidents of the line-circuit the samemay be readily repaired without rendering the circuit inoperative forany considerable length of time.

Referring now to Figs. 7 and 8, the current in the normal condition ofthe circuit, as indicated in Fig. 8 by arrow 20, passes through thegalvanometer and electro-magnet back over the line-wires, whereas whenthe thermostatis operated and the polarity reversed the current passesthrough the electromagnet and galvanometer back over the line.

In practice it might happen that the current would be reversed by theoperation of one thermostat, the alarm sounded,and the pointer cdeflected to the indication marked fire, and immediately after a secondthermostat might be operated and the current-again reversed and thecurrent restored to its normal direction, thus restoring the parts ofthe receiving-instrument to their normal condition.

In order that the operator may know positively whether the alarm is dueto a fire,- I have provided a detent or catch a (see Figs. 1 and 2) forthe pointer 0 the said detent or catch being located near the fireindication and adapted to engage the pointer 0 when the latter has beenmoved to the fire indication by the reversal of the current. So, also, Iprefer that the polarized armature should be withdrawn by its spring (lwhen repelled from its magnet sufficiently far to remove it from theinfluence of its magnet, thus requiring that the said armature bereplaced in operative position by the operator.

I claim-- 1. In an automatic fire-alarm system, the combination, with amain-line circuit, an elec tro-magnet located therein and provided witha polarized armature, and a receiving-instrument controlled in itsoperation by the said but adapted to be included inthe said circuit bythe melting of the fusible connection to reestablish the main line withreversed polarity after the said line has been opened by the operationof the fusible connection, substantially as described.

2. In an automatic fire-alarm system, the combination, with a main-linecircuit, an electro-magnet located therein and provided with a polarizedarmature, and an audible signal controlled in its operation by the saidpolarized armature, of a pole-changing thermostat located in themain-line circuit and consisting of two sets of pole-changing arms, oneset being normally connected in the main line by a fusible connectionand the other set being normally not included in the said circuit, butadapted to be included in the said circuit by the melt-ing of thefusible connection to reestablish the main line with reversed polarityafter the said line has been opened by the operation of the fusibleconnection, substantially as described.

3. In an automatic fire-alarm system, the combination of the followinginstrumentalities, viz: a main-line circuit, an electro-magnet locatedin said circuit and provided with a polarized armature, a visualindicating device included in the main-line circuit, and a pole-changingthermostat adapted to be operated by increase in temperature to reversethe polarity of the main line and operate the V18 ual indicatorreversely, substantially as described.

t. In an automatic fire-alarm system, the combination of the followinginstrumentalities, viz: a main-line circuit, an electro-magnet locatedtherein, an audible signal con trolled by the said electro-magnet, avisual indicating device operated by changes in condition of thecircuit, and a pole-changing thermostat, substantially as described.

5. A pole-changing thermostat having two sets of pole-changing arms, oneset consisting of conducting-springs held in tension by fusible solderand in position to conduct the current in one direction, the other setof polechanging arms being connected to the said springs and normallynot included in the linecircuit, but which are included therein by theoperation of the said springs to reverse the line-current when saidsprings are released, substantially as described.

6. The herein-described pole-changingthermostat consisting of a base,conductingsprings secured thereto at one end and pro- IIO vided withpoie'changing arms, conductors on In testimony whereof I have signed myI said base, fusible conneet-ionsjoining the said name to thisspecification, in the presence of conducting-springs to the saidconductors, two subscribingwitnesses,thisSth dayof Auandcircuit-terminals with which the polegust, A. D. 1891.

5 changing arms co operate vh'en the said T springs are released by Lhemelting'of the fnsi- GILMAN ble connections to reestablish the saidcircuit \Vitnesses:

and reverse the polarity of the same, snbstan- O. F. BROWN,

tially as described. A. D. HARRISON.

